Organism 96 (Tales of Terror).

Prose BBC Books's seasonal anthology publications continue with Tales of Terror, stories set in and around my birthday. Having done Christmas and Halloween now, perhaps they'll branch out into other holidays, although Big Finish already covered a few of those back in the day, not that most of us can afford to buy those collector's items now.  Organism 96 is Paul Magrs writing his first full on prose Eighth Doctor story in over a decade and it has everything you might expect from his stories.  A whimsical adversary born of mythology (albeit with a scientific origin), some hard core fan references and lashings of meta-fictional subtext.  The Doctor's enjoying a cruise when the ship takes on a passenger, an old lady, who isn't who she seems to be.  It's just the sort of simple premise which works well with these short trips.  The story's largely told from the point of view of a one off companion, Marie, one of the ship's entertainers, and is the sort of character who'd be played by a famous singer who can act or vis-versa in a television version.  Magrs's version of the Eighth Doctor is perfection.  Magrs was one of the key architects of the character back in the day (through his first novel about him The Scarlet Empress) and although this isn't some great continuity deep dive, this is very much the same man who originally appeared in those old novels.  So rare to find an Eighth Doctor story not set during the Time War now.  Superb. 
Placement:  My guess is pretty early, perhaps in the Greenpeace gap but it could be anywhere.  I've contacted Paul Magrs to see what he says [update: he "liked" the tweet so I'll leave it there].